One of the consequences of pervasive computing that we're going to have to grapple with is the proliferation of devices that accidentally preserve confidential information about us. One example: photocopiers.

[M]ost digital copiers manufactured in the past five years have disk drives — the same kind of data-storage mechanism found in computers — to reproduce documents. As a result, the seemingly innocuous machines that are commonly used to spit out copies of tax returns for millions of Americans can retain the data being scanned.

If the data on the copier's disk aren't protected with encryption or an overwrite mechanism, and if someone with malicious motives gets access to the machine, industry experts say sensitive information from original documents could get into the wrong hands.

Some copier makers are now adding security features, but many of the digital machines already found in public venues or business offices are likely still open targets, said Ed McLaughlin, president of Sharp Document Solutions Company of America.

"You actually have a better chance at winning 10 straight rolls of roulette than getting those hard drives on copiers rewritten," he said….

Sharp was among the first to begin offering, a few years ago, a security kit for its machines to encrypt and overwrite the images being scanned, so that data aren't stored on the hard disks indefinitely. Xerox Corp. said in October it would start making a similar security feature standard across all of its digital copiers.